WTF

- login.php
<?php
session_start();
if(isset($_POST['login'], $_POST['password'], $_POST['password2'])) {
    if($_POST['password']==$_POST['password2']) {
        try {
            define("DBTYPE", "mysql");
            define("DBHOST", "localhost");
            define("DBNAME", "lab12");
            define("DBUSER", "root");
            define("DBPASS", "root");
            $db = new PDO(DBTYPE . ':host=' . DBHOST . ';dbname=' . DBNAME,DBUSER,DBPASS);
            $name = $_POST['login'];
            $pass = $_POST['password'];
            $db -> exec("USE lab12");
            $query = "SELECT * FROM users WHERE login=:name";
            $prep = $db->prepare($query);
            $prep->bindParam(':name',$name);
            $prep->execute();
            if($prep->rowCount()!=0) {
                $res = $prep->fetch();
                if($res[2]==$pass) {
                    $_COOKIE['name'] = $name;
                    $_COOKIE['pass'] = $pass;
                    $_COOKIE['signedin'] = true;
                } else {
                    $_SESSION['error'] = true;
                    $_SESSION['err_type'] = "Wrong password.";
                    header('Location: signin.php');
                    exit;
                }
            } else {
                $_SESSION['error'] = true;
                $_SESSION['err_type'] = "User not found.";
                header('Location: index.php');
                exit;
            }
        } catch (PDOException $e) {
            $_SESSION['error'] = true;
            $_SESSION['err_type'] = "Unsuccessful SQL transaction. Please try again later.";
            header('Location: index.php');
            exit;
        }
    } else {
        $_SESSION['error'] = true;
        $_SESSION['err_type'] = "Passwords do not match.";
        header('Location: index.php');
        exit;
    }
} else {
    $_SESSION['error'] = true;
    $_SESSION['err_type'] = "Please try again.";
    header('Location: signin.php');
    exit;
}
?>